This invention relates to planetary gear type rotary mechanical actuators and more particular to an actuator which is used in series with at least one other actuator and which disconnects itself from the series and from the load if it jams and allows the transmission of power to the other actuators in the series.
In aircraft flight control, actuators are used on the leading edge flaps, the trailing edge flaps, ailerons, flaperons, and rudders in order to adjust the surfaces to the desired position. Trailing edge surfaces and rudders are referred to as the primary flight control surfaces since their position is critical in aircraft control. It is imperative therefore that control of these flaps or surfaces is not compromised. Until now, because of the possibility of jamming of the rotary mechanical actuators, the primary flight control surfaces have used linear hydraulic actuators since they typically fail "open" and it is easy to override the hydraulic actuator in order to use a back up actuator to lock the control surface in a neutral position.
On the other hand, the leading edge of an aircraft wing is referred to as the secondary flight control surface since the loss of its use restricts aircraft performance, but does not cripple the aircraft. Because of this difference, mechanical actuators, either linear or rotary, are used on the leading edge of an aircraft. If an actuator jams, it is permissible that the flap be allowed to lock in the jammed position. However, a jammed actuator can cause damage to the aircraft wing if one continues to drive the jammed actuator. Therefore, there is a need for an actuator which is designed to reduce the possibility of jamming and if it jams, to disconnect itself from the actuation system and to allows the transmission of the driving torque to the other actuators downstream of the jammed actuator.
Furthermore, an actuator which is used in series with several other actuators and which can disconnect itself from the system if it becomes jammed, can be used on the primary flight control surface was well as the secondary flight control surfaces.